1. Field of the Invention
This invention relates generally to caisson gripping apparatus, and more particularly to a gripper device associated with land or marine columns, poles, posts, caissons, pilings, and the like for connecting a base or platform structure thereto.
2. Brief Description of the Prior Art
Suspended bridges and causeways are often made up of a plurality of prefabricated platform sections which are interlocked end to end to span a waterway. Columns, such as caissons or pilings are installed vertically through the corners of the platform sections after they have been laid into position and the platfrom is secured to the columns. A great deal of time is spent in leveling the platform and securing the platform to the columns in a level position. This process may also be hampered by the movement or slippage of the securing means due to wave action.
Gripping assemblies are known which are used to connect the decks of barges or offshore platforms to columns, caissons, pilings, and the like. There are several patents which disclose gripping assemblies of various construction.
Suderow, U.S. Pat. No. 2,870,639 discloses a gripper and jack assembly having an upper and lower gripper which are selectively controlled to grip the column. Each gripper comprises an annular segmented ring with a plurality of slips movably carried on the inner side. The slips are mounted on each ring segment by flexible straps at their top and bottom ends which permits independent vertical movement of the ring segements and radial or lateral displacement of the slips relative to the ring. The diameter of the ring segments is contracted or expanded by a wedge operated by a fluid cylinder. The slip members have outwardly extending lugs which have a tapered wedge surface received on a corresponding tapered wedge surface in lugs on the ring segements whereby relative vertical movement between the members will cause the slips to grip tighter.
Suderow, U.S. Pat. Nos. 2,873,580 and 2,948,119 disclose a gripper assembly used in conjunction with a jacking mechanism comprising an outer pressure ring which is positioned above an opening in a deck and has circumferentially spaced inclined inner surfaces which engage complimentary inclined surfaces on gripper slips. Circumferentially spaced bolts extend vertically through the pressure ring and holes in the deck. The threaded ends of the bolts are connected to the underside of the deck by a locking nut. Eyelets on the slip and pressure ring receive an inclined rod. C-shaped stop members surround the pressure ring and have a flange which engages a flange on the pressure ring to limit the upward movement of the pressure ring.
Smith, U.S. Pat. No. 2,858,105 discloses a jacking assembly utilizing a gripper assembly having slip wedges spring supported from the deck.
Lucas, U.S. Pat. No. 4,041,711 discloses a hydraulically operated slip assembly which utilizes a T-shaped member between the slips to engage the outer wall of adjacent slips.
Lucas, U.S. Pat. No. 2,858,105 discloses a cable type gripper.
The present invention is distinguished over the prior art in general, and these patents in particular by gripper devices installed in the spudwells of a platform or causeway section and manually operated to grip the pile to suspend the platform or causeway section in a level position on the piles. Each gripper device has a cylindrical bowl with a flat mounting flange at the bottom end. The bowl has large central bore extending from the top end and terminating in a smaller bore at the bottom end defining a shoulder therebetween. A series of circumferentially spaced actuator segments having a vertical outer wall and a radial flange at the top end are mounted within the bowl by bolts for vertical movement relative to the bowl. The actuator segments have a downwardly and radially outwardly tapered interior wedging surface with a T-shaped slot extending along the wedging surface. A series of slip segments have a toothed interior surface for gripping the pile and a tapered exterior wedging surface corresponding to the wedging surface of the actuator segments. A headed guide button secured to the slip rides in the T-shaped slot to guide the slips along the wedging surfaces.
The piles are lowered through the bowl and set into the seabed and the platform or causeway section is leveled horizontal. As the bolts are tightened, the actuator segments move vertically downward relative to the bowl and the wedging surfaces engage to wedge the slips radially inward to firmly engage and grip the exterior surface of the pile.